EGFR and neoplasm: Additionally, as a main molecular mechanism of resistance to osimertinib, EGFR C797S mutation was acquired in 6.4% (7/109) of patients receiving the first-line treatment of osimertinib by plasma ctDNA detection14 and in 1.4% (1/74)21 and 15.2% (7/46)23 of patients receiving the first-line treatment of osimertinib by tumor tissue detection.